Methods for producing manganese in metal state and pure manganese dioxide, if desired, from manganese ores



' solution of MnSOr and Fe2(SO4) Say for the purpose of treating 100 kg. of pyro- Patented Aug. 22, 1944- METHODS FOR PRODUCING MANGAN IN METAL STATE AND PURE MANGANESE DI- OXIDE, IF DESIRED,

ORES

FROM. MANGANESE Pietro Guareschi', Genoa, Italy; vested in the Alien Property Custodian .No Drawing. AppIicationJSeptember 18,- 1941, Serial No. 411,430. .In Italy October 8, 1940 This invention has ior its object a producing-metallic manganese and'if'desired pure manganese dioxide, from manganese ores.

In the method of this invention the manganese ore is converted into manganese sulphate by solution in sulphuric acid or, at least in part, by the anolyte recovered from a final electrolysis step in the process, and by operating in presence of a reducing agent which converts the manganese dioxide, being by itself only slightly responsive to'attack by diluted acids, into manganese monoxide which on the contrary is easily attacked. A mixed solution of manganese sul- -phate and of'sulphate of the element used as reducing agent is thus obtained; said solution is subsequently neutralised for the precipitation of the .reducingagent from the solution and the latter is subsequently carried again into the process.

Finally the solution of manganese sulphate is electrolysed and thus metallic manganese and,

-if desired, pure manganese .dioxide is obtained;

the electrolysis is carried out with advantage in such a manner as to obtain and keep the anolyte and catholyte separate for their re-use in the process.

As reducing agent a solution'of a soluble iron salt in ferrous state is used with advantage since -most of impurities presentinthe ore and consisting usually mainly of iron, arsenic,antimony,

-etc. precipitate with said salt at the time of the neutralisation step. r

An embodiment of theamethod of this invention is hereinafter described by way of example assuming that pyrolusite is treated and that iron is used as reducing agent.

Pyrolusite is dissolved by means of sulphuric acid in the presence of ferrous sulphate which acts as a reducing agent; the manganese oxides are'thus reduced into manganese monoxide and are dissolved by sulphuric acid thus producing a lusite having a 50% content of M1102, 70 kg. of iron are used said iron being recovered in the process,.and 600 kg. of diluted (20%) sulphuric acid,.this acid also being recovered.

The removal of impurities of the class of cop- I per, zinc, cadmium, etc., from the. solution is, ef-

fected by precipitating saidmetals by pure electrolytic manganese in powder state, said manganese being taken from the manganese obtained by electrolysis in the final step of the process. 4 Subsequently iron is precipitated by neutralising the solution; said neutralisation may be ef- 1 Claim. (01. 204-105) method for.

fected as usually by means of calcium carbonate or ammonia gas or in solution in presence of ammonium salts, or preferably, in accordance with this invention, by taking advanfageof the catholyte recovered from the subsequent electrolysis stepand consisting of an alkaline solution of ammonium salts with manganese sulphate;

.forsuch apurpose the electrolysis step is carried out with the aid of porous separating partitions in conditions proper to obtain the catholyte separately.

The neutralisation step may be improved by having the residual ferrous salts, if any, converted into i'erricstate by a Previous addition ofmanganese dioxide obtained in theelectrolysis step.

The ferric hydrate which precipitates as an effect of the neutralisation may be regenerated into ferrous sulphate which is subsequently carried'again in the process in the ore solution step; for this purpose the ferric hydrate is dissolved in sulphuric-acid in the presence of sulphur dioxide or of an alkali sulphide or, in accordance with a feature of this invention, in the anolyte recovered from the electrolysis stepand consisting of an acid solution of manganese sulphate and-of. ammonium sulphate.

The solution thus obtained, consisting of pure manganese sulphate, is treated by an electrolysis step in which manganese in metal state is obtained at the cathode, a portion of said mang'anese being usedif desired for the purification of the solution as above stated; by a proper control of the electrolysis step it is also. possible to obtain pure manganese dioxide on the anode, which may be used in oxidising steps preceding the neutralisation step.

Theelectrolysis is effected with advantage by means of cells having porous partitions to secure the separation of the anolyte and catholyte from each other; in these circumstances the acid anolyte is obtained separately for further use either in the attack of the ore or'for regenerating the ferric hydrate which has been precipitated as an 'efiect of the neutralisation step, said ferric hydrate being regenerated into ferrous sulphate by treatment with said anolyte in presence of a reducing agent; on the other hand the recovered catholyte may be used again in the process for neutralizing the acid solution of manganese sulphate, ferric sulphate and ammonium sulphate.

What I claim as myinvention and desire to secure by United States Letters Patent is-:

The cyclic process of producing metallic manganese from impure manganese dioxide ores,

which'consists in treating the ore with sulphuric anolyte and acid in the presence of ferrous sulphate; adding metallic manganese to the resulting solution to precipitate metal impurities less electro-positlve' than manganese, adding manganese dioxide to convert the iron to the ferric state, neutralizing the solution by the addition of an alkali to precipitate ferric iron, filtering out the latter, electrolyzing the filtrate in a diaphragm-type cell to deposit metallic manganese at the cathode and generate the solution and returning it to the ore dissolving step.

PIETRO GUARESCHI. 

